201829520187611177FF8B4167FFBFFFA3F22FD43BFFCED86691658359-00AE-4319-ACBC-E9C544599C5B3220182042018Ruttapon Srisonchai, Henrik Enghoff, Natdanai Likhitrakarn, Somsak PanhaThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Abstract

The dragon millipede genus Desmoxytes Chamberlin, 1923 is one of the most spectacular genera in the large family Paradoxosomatidae. The genus currently contains 45 described species which are broadly distributed in China, Laos, Malaysia, Myanmar, Thailand, and Vietnam. The “tramp” species D.planata (Pocock, 1895) has become widely dispersed to Fiji, French Polynesia, India, Indonesia, Seychelles, and Sri Lanka (Attems 1936, Chamberlin 1923, 1941, Golovatch and Korsós 1992, Jeekel 1980b, Mauriès 1980, Ramage 2017, Shelley and Lehtinen 1998, Tikader and Das 1985). Most species are best represented in or even restricted to limestone habitats and caves (Enghoff et al. 2007, Liu et al. 2014, 2016, Srisonchai et al. 2016), and some are probably troglobites (Loksa 1960, Golovatch et al. 2010, 2012, Liu et al. 2014, 2016).

Desmoxytes has been taxonomically discussed on several occasions (Jeekel 1964, 1980a, Golovatch and Enghoff 1994, Golovatch et al. 2012). The genus was revised by Golovatch and Enghoff (1994), and further variable gonopod characters were added to the diagnosis by Golovatch et al. (2012). Several new species were described recently (Liu et al. 2014, 2016, Likhitrakarn et al. 2015, Golovatch et al. 2016, Srisonchai et al. 2016). However, for the time being, no updated diagnosis exists for Desmoxytes.

Intensive field surveys focusing on this genus were made by our team (ASRU), mainly in Southeast Asia (Malaysia, Myanmar, Laos, Thailand). After examination of newly collected specimens, and comparison with type material of all congeners, we found distinctive morphological characters, mainly in gonopods and paraterga, indicating heterogeneity of Desmoxytes s.s. A preliminary study on phylogeny of dragon millipedes based on mtDNA and nuclear DNA shows a perfect congruence with morphology (Srisonchai et al. 2017) and further indicates that Desmoxytes as hitherto understood (i. e., sensuGolovatch and Enghoff 1994) is not a monophyletic taxon. Therefore, we find it necessary to subdivide the dragon millipedes into five genera. In the present study, the first in a series of articles about dragon millipedes, Desmoxytes is re-diagnosed, and the four other genera (Hylomus Cook & Loomis 1924, and three new genera yet to be named) are outlined. Ten species of Desmoxytes in the new, restricted sense are revised, eight new species are described, a new identification key to Desmoxytes species is provided, and 33 Desmoxytes species are assigned to the reinstated genus Hylomus.

Materials and methodsSpecimen collecting and preservation

The specimens were collected by hand from different localities in China, Laos, Malaysia, Myanmar, and Thailand during the rainy season. The GPS coordinates were recorded by using the Garmin GPSMAP 60CSx and the elevation was obtained by checking in Google Earth.

Intensive surveys in several parts of those countries, especially in Thailand, have been made since 2007 by staff and students from Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, referred to as “ASRU members” in the lists of material. Specimens were preserved in 70% ethanol for morphological study and partly in 95% ethanol for molecular study.

Illustrations

Photos of living specimens were taken in the field and after collecting using a Nikon 700D+AFS VR 105 mm lens. The gonopods were illustrated with a scanning electron microscope (JEOL, JSM–5410 LV); gonopods were coated with gold and mounted on aluminium stubs, and after imaging the gonopod was removed from the stub to be kept in dry condition. Drawings were made using dot-line techniques under a stereo microscope.

Morphological descriptions

General descriptions of the tribe and of the genus are provided. All specimens were carefully examined for non-gonopodal (male, female and juvenile) and gonopodal characters under a stereo microscope. Non-gonopodal characters were examined those of size, colour, head, antenna, collum, tegument, prozona, metaterga, paraterga, telson, sterna and legs. We use the terms of gonopod morphology from previous papers (Pocock 1895, Chamberlin 1923, 1941, Attems 1937, Jeekel 1964, 1980a, Zhang 1986, Jeekel 2003, Golovatch and Enghoff 1994, Enghoff et al. 2007, Srisonchai et al. 2016), in part adapted, and we add further morphological characters (see Table 1).

Table 1.

Gonopod structures in Desmoxytes s.s., and their abbreviations (in Bold: structure only occurring in certain species).

Gonopodal part

Abb.

Description

Acropodite

The apical part of the gonopod; including femorite, solenophore, and solenomere.

Coxa

cx

The basal part of the gonopod, connecting to body ring, attached to the apertural rim dorsally; rather stout; ca. half as long as femur, sometimes quite short (equal in length with prefemur); with distoanterior group of setae.

All holotypes, some paratypes of the new species, and most additional specimens will be deposited at CUMZ. Some paratypes and some new specimens will be donated to NHMUK, NHMW, ZMUC, and ZMUM.

All species of Desmoxytes s.s. have been examined, notably Pocock’s specimens in NHMUK, type material of Hylomusdraco in USNM, and some material in ZMUC. Figure 1 shows original labels of the type material for Desmoxytesplanata, D.cervina, D.taurina, and Hylomusdraco.

ZMUC Natural History Museum of Denmark (Zoological Museum), University of Copenhagen, Denmark

ZMUM Zoological Museum, University of Moscow, Russia

Other abbreviations used in the text

a.s.l. above sea level

ca. approximately, around (circa)

FFI Fauna and Flora International, Myanmar

Positional/directional terms in gonopod description

Morphologically the gonopods are traditionally depicted as rotated 90° up from their position in situ.

Dorsal refers to a position on the side nearest to the body ring. Ventral refers to a position on the side farthest away from the body ring. Mesal refers to a position on the side nearest to the midline. Lateral refers to a position on the side away from the midline.

Dorsad refers to a direction towards the body ring. Ventrad refers to a direction away from the body ring. Mesad refers to a direction towards the midline. Laterad refers to a direction away from the midline.

“Sub-” is used as a prefix to indicate positions and directions slightly different from the ones given above. For example, “submesal” means a position close to, but not quite on the mesal side.

The tribe Orthomorphini was established by Brölemann (1916), as belonging to family Strongylosomidae. Later, the correct name for this family was found to be Paradoxosomatidae (Jeekel 1963). The tribe Orthomorphini is characterised by the following gonopodal characters:

3. Apical part of telopodite consisting of a solenophore supporting the solenomere. The solenophore consists of a lamina lateralis and a lamina medialis.

4. Most species without a femoral process and a tibiotarsal process.

The tribe Orthomorphini currently contains 22 genera (Nguyen and Sierwald 2013). Around 200 named species have been recorded so far. The tribe is broadly distributed mainly in Southeast Asia (Cambodia, Indonesia, Laos, Malaysia, Myanmar, Thailand, Vietnam, a few synanthropic species more or less globally widespread).

Subdivision of Desmoxytes s.l.

It is here proposed to split Desmoxytes s.l. into five groups. These groups are morphologically distinct, as detailed below, and are all supported by a molecular phylogeny (work ongoing). The molecular phylogenetic tree yields five groups of Desmoxytes s.l., and Orthomorpha Bollman, 1893 and Antheromorpha Jeekel, 1968 appear as ingroups. Desmoxytes s.l. thus comes out as non-monophyletic (Srisonchai et al. 2017).

The present paper deals with one of the five groups, viz., Desmoxytes s.s. The remaining species (see Table 2) will be assigned to their proper genus in forthcoming papers. For one of the groups, a genus name is already available, viz, Hylomus Cook & Loomis, 1924, and this name is herewith re-instated as a valid genus name.

Table 2.

Species assigned to Desmoxytes s.l. and their placement according to our analysis.

The ‘spiny’ group, still without described members, differs from the others by the following combination of characters: paraterga spiniform; tegument of metaterga smooth (some species microgranulate); gonopodal telopodite straight; postfemur conspicuous, narrow laterally, demarcated from femur by deep mesal and lateral sulci; lamina lateralis obviously demarcated from lamina medialis; lamina lateralis smaller than lamina medialis (lamina lateralis very small); lamina medialis long and curved, without process and lobe (Figs 2D, 3G).

The fifth group, corresponding to genus Hylomus and including numerous species, has wing-like, antler-like or spiniform paraterga, but is well-defined by gonopod characters: postfemur inconspicuous or absent (mesal and lateral sulci shallow or absent), lamina medialis short (except in a few species), lamina medialis mostly without lobe and process (except some species which have a process, a spine or a hook) (Figs 2E, F, 3H–P).

As Figs 2 and 3 clearly show, the differences in morphology (paraterga and gonopod) easily allow separation of the five groups of Desmoxytes s.l. species.

The distribution of each group based on data from both described and undescribed species is as follows:

Hylomus was established as a monotypic genus by Cook and Loomis (1924), who were so impressed by the remarkable external features of the type species, H.draco Cook & Loomis, 1924, viz., the strongly elevated paraterga (like trees), that they placed the new species not only in a new genus but even in a new family, Hylomidae.

Jeekel (1964, 1968) maintained Hylomus as a valid genus, including only H.draco, and moved it into family Paradoxosomatidae, stating that the genus Pratinus Attems, 1937 (=Desmoxytes) was closely related to Hylomus.

Later, Jeekel (1980a) re-assessed the generic allocation of all members of Hylomus, Desmoxytes Chamberlin, 1923, Pratinus Attems, 1937, Prionopeltis Pocock, 1895 and Ceylonesmus Chamberlin, 1941, leading to the recognition of three genera: Hylomus, Desmoxytes (= Prionopeltis, Pratinus, Ceylonesmus) and Pteroxytes Jeekel, 1980. Jeekel (1980a) stated that the morphological characters of Hylomus showed clear differences from Desmoxytes and Pteroxytes (paranota antler-shaped and detail of gonopodal apex). The same author emphasised that his work was just a preliminary outline, and that “the discovery of new species … may considerably change the picture”.

Golovatch and Enghoff (1994) disagreed with Jeekel’s idea (1980a) to maintain Hylomus and Pteroxytes as separate genera. Based on new evidence from examination of old and new material, previous literature and the first cladistic analysis based on morphology, the authors synonymised Hylomus and Pteroxytes under Desmoxytes and assigned the genus to tribe Orthomorphini, of which they regarded Hylomini a synonym.

As mentioned above, our morphological analysis, as well as the initial molecular study, support recognition of Hylomus as a valid genus in agreement with Jeekel (1980a). We therefore consider Hylomus as a valid genus, separate from Desmoxytes. We further reallocate 33 species of Desmoxytes s.l. from China (19 species), Vietnam (ten species), Laos (three species) and Thailand (one species) to Hylomus (see Table 2).

For DesmoxytessensuGolovatch and Enghoff (1994) we will retain the name “dragon millipede”, originally coined by Cook and Loomis (1924) for Hylomusdraco. Golovatch et al. (2012) outlined the history of the name “dragon millipede” and further argued that Desmoxytesphilippina Nguyen & Sierwald, 2010 (Philippine Isl.), and Desmoxytoideshasenpuschorum Mesibov, 2006 (Australia) have been wrongly assigned to Desmoxytes and “dragon millipedes”, respectively.

Diagnosis.

Desmoxytes s.s. differs from other genera of Orthomorphini by the combination of the following characters:

The description applies to adult males and females, except for the gonopods section and when “male” is specified (Figs 5, 6, 7, 8). The description hereunder is mainly based on illustrations of D.planata.

COLLUM (Fig. 6A, C): With 1–3 transverse rows of setae/tubercles, the exact number in each row varying between species (sometimes lateral setae/tubercles of anterior row located nearly at the base of paraterga, on anterior margin). Paraterga wing-shaped, usually elevated at ca. 0°–30°.

From south China to Malaysia. Most species seem to be local endemics (only D.planata is dispersed, certainly by anthropochory, through mainland Southeast Asia and in many islands). Desmoxytes specimens were usually found by ASRU personnel in limestone habitats or on granitic mountains, and some were seen crawling on rocks or vegetation or tree branches (Figure 4).

Known only from Surat Thani and Nakhon Si Thammarat Provinces. All specimens were collected in limestone mountains (on the mainland and on two islands) (Fig. 9E). We also surveyed other islands in Mo Ko Ang Thong National Marine Park, but found no specimens of D.aurata sp. n. The new species is probably distributed along the islands in the Gulf of Thailand and also on the mainland near the type locality. We regard it as endemic for Thailand.

Desmoxytesaurata sp. n. is morphologically similar to D.delfae and D.perakensis sp. n. in the remarkable orange colouration, as well as some morphological characters (except characters in diagnosis). These three species show allopatric distribution ranges, and the big mountain ranges known as the Nakhon Si Thammarat and Sunkala Khiri mountains possibly act as dispersal barriers.

Remarks.

The bright orange colouration is without doubt aposematic. There is some distinct variation within populations in the sternal lobe between male coxae 4, especially its shape: in most specimens the lobe is subrectangular, in others subtrapeziform, and its tip also varies – subtruncate/ subemarginate/ round. The shape of the sternal lobe of the new species is similar to that seen in D.delfae and D.perakensis sp. n., however, it looks thinner than those when seen in lateral view.

Coexisting species.

Desmoxytescervina was found together with the new species in some localities.

ANTENNAE: Long and slender, reaching to body ring 6 (male), and 5 (female) when stretched dorsally.

COLLUM: With 3 transverse rows of setiferous tubercles, 3+3 anterior, 1+1 intermediate and 2+2 posterior tubercles (excluding small setiferous notches at base of paraterga), lateral tubercles of posterior row located at almost halfway to intermediate row; paraterga of collum low, elevated at ca. 30°, directed caudolaterad, with two setiferous notches on lateral margin (first inconspicuous notch located at the base of paratergum, second one conspicuous).

Known only from the type locality and nearby areas. Desmoxytesbreviverpa was collected from limestone forest, crawling on logs and litter (Srisonchai et al. 2016). We believe it may be distributed though the central and southern parts of north Thailand. This species has been reported from Phrae, Lampang and Uttaradit Provinces. Therefore, D.breviverpa should be regarded as endemic for Thailand.

Remarks.

Specimens collected from Uttaradit Province south of the type locality showed the same morphological characters as the type specimens. No variation was found between populations although most limestone areas in north Thailand are geographically isolated by several big mountain ranges and quite far from each other.

Srisonchai et al. (2016) discussed variation of the tip of sternal lobe between male coxae 4; we found additional variation within populations as follows:

– Tip of sternal lobe in some specimens almost truncate (=subtruncate), albeit other specimens show an emarginate tip (slightly or deeply emarginate).

– Tip of hypoproct in some individuals subsemicircular, in others subtrapeziform.

– Tip of process (plm) of lamina medialis emarginate in most specimens, but almost blunt in some.

Coexisting species.

None known.

Corrections to Srisonchai et al. (2016)

Srisonchai et al. (2016, pp. 99–103) wrote in the description of this species that the paraterga (including paraterga of collum) are directed dorsolaterad. In fact they are directed caudolaterad as described above.

Desmoxytescervina is known from Myanmar (Lenya National Park) and Thailand (Chumphon, Krabi, Nakhon Si Thammarat, Phang Nga, Phuket, Ranong, and Surat Thani Provinces). The type locality is in south of Tenasserim, but we do not know the exact location, probably somewhere near Taninthayi township. The locality of the paralectotype (see below) “Malewoon, Tenasserim”, is currently known as Maliwan Village.

Almost all specimens were collected from limestone habitats, a few specimens were collected from granitic areas. Interestingly, D.cervina was also found in some islands in both the Andaman Sea and the Gulf of Thailand (Mu Koh Surin National Park, Phuket, and Ko Samui).

Decker (2010) classified “D.pterygota” as endemic for Thailand due to its narrow range near the type locality. After intensive collecting and synonymising of D.cervina and “D.pterygota”, the known distribution range has expanded to southern Myanmar and southern Thailand.

This species was found living together with D.delfae and D.corythosaurus sp. n. According to our observations, it is probable that they may even share microhabitat: humid rocks, branches of trees and rock walls.

Note on material.

This species was described based on two males, one of which was collected by L. Fea (Malewoon, Tenasserim – MSNG) and the other collected by E. W. Oates (south Tenasserim – NHMUK).

Jeekel (1964) revised this species by examining the male in MSNG; he stated that “in anticipation of the designation as holotype of the specimen collected by Oates in the British Museum, I have labelled this specimen as paratype”. However, the holotype has never been designated in the original description. R.L. Hoffman visited NHMUK and labelled the specimen collected by Oates as paratype, but he did not publish this designation, which is in conflict with Jeekel’s (1964) paratype designation. Therefore, we here designate the male collected by Oates and belonging to NHMUK as lectotype to stabilise the name. The male in MSNG (which we have not examined) is considered to be a paralectotype.

Some specimens kept in MHNG and identified as “D.pterygota” by Decker (2010), are probably D.cervina because the localities fall within the distribution range of this species.

Remarks.

This is the first report of the colour of living specimens for this species; the brownish red colour is apparently aposematic. Pocock (1895) and Golovatch and Enghoff (1994) did not mention the colour of living specimens. We found two colour morphs of D.cervina: brownish red and brown. The majority of specimens are brownish red, and the minority are brown; the latter colour can be found in a few specimens within a population.

Interestingly, brownish red and brown morphs occur in the same habitat in the valley behind Tiger Cave and Ban Song Phi Nong. The brown morph was found at Wat Tham Kanlaya Namit, Wat Tham Thong Phannara, Tham Nam Pud, Phung Chang Cave and Wat Suwan Khuha (Monkey Cave). Specimens from the remaining localities are of the brownish red morph. We examined the morphological characters of all specimens of both colour morphs; all specimens exhibit the same morphology, especially in the gonopods which are identical. Perhaps the difference in colour is caused by environmental factors and/or genetic variation.

We assume that the type material of both D.cervina, collected by Oates and Fea a hundred years ago, and “D.pterygota” collected by M. Andersen and A.R. Rasmussen 17 years ago, did probably exhibit brownish red colour because all specimens near the type localities are brownish red. We found additionally that the colour of some females is pale brownish red or pale brown, and the colour of juveniles is pale brown.

Jeekel (1964) wrote in his redescription that D.cervina shows collum without setae, metaterga 2–19 with 1+1 anterior tubercles and 2+2 posterior tubercles. Golovatch and Enghoff (1994) distinguished “D.pterygota” from D.cervina by having smooth metaterga. They also described “D.pterygota” as having no pleurosternal carinae, antenna reaching to ring 4 in male, collum with 2 rows of 3+3 anterior setae and 1+1 intermediate setae, metaterga 2–19 with 2+2 anterior cones and 2+2 posterior cones. After examination of all type material and newly collected specimens of D.cervina and “D.pterygota”, we found that:

– all specimens of D.cervina and “D.pterygota” display fine microgranulation on the metaterga.

– all specimens have pleurosternal carinae, in body ring 2 very distinct and crest-like, in ring 3 very small, thereafter absent.

– antenna reaches to ring 6–7 in male and to ring 5–6 in female of both D.cervina and “D.pterygota”.

– collum has 3+3 anterior setae in all specimens – because Jeekel studied old preserved specimens, the setae may have been lost over time.

– size of tubercles on metaterga: tubercles conspicuous in some specimens, inconspicuous in the others (bigger and more obvious in the holotype of “D.pterygota” than in the lectotype of D.cervina).

– tip of process (plm) of lamina medialis: in some specimens terminating in one blunt process, in others terminating in a sharp spine.

– shape of sternal lobe between male coxae 4: in some individuals subtrapeziform, in others subsemicircular.

– tip of sternal lobe between male coxae 4: in some specimens round, in some subtruncate, in others emarginate.

– cross-impressions on sternum: in some individuals shallow and faint, in others slightly deep.

– tip of epiproct: in some individuals truncate, in others slightly emarginate.

– caudal margin of hypoproct: in some specimens slightly round, in others subtruncate.

– size of sternal lobe between male coxae 4 when seen in lateral view in specimens from Wat Satit Khirirom: in some specimens thick, in others thin.

II. variation between populations

– colour: all individuals in the same population usually have the same colour: brown or brownish red. However, in some populations (valley behind Tiger Cave and Ban Song Phi Nong) brownish red and brown individuals coexist.

Although the male paralectotype of D.cervina (in MSNG) has not been examined by us, the morphological characters for this specimen as redescribed by Jeekel (1964) perfectly match the morphology of the numerous other specimens we have seen. Based on our analysis of morphology and variation of these specimens we have synonymised “D.pterygota” under D.cervina.

Distribution data support the synonymisation: the type localities of “D.pterygota” (Ranong Province) and D.cervina (Tenasserim = Taninthayi) are very close to each other. Our intensive surveys prove that this species is distributed quite widely, but nevertheless is found in south Myanmar and south Thailand only.

During the field survey, we noticed several adult males of D.cervina which were infested with red mites. The mites are probably larvae of the genus Leptus Latreille, 1796 (Prostigmata, family Erythraeidae). Associations between mites and millipedes may be of a phoretic or a parasitic nature (Gerdeman et al. 2000, Swafford and Bond 2010, Farfan and Klompen 2012, Mwabvu 2014). In Fig. 17C and D, several engorged mites are seen along with a few small, non-engorged ones, and we therefore assume that the mite species found in D.cervina is parasitic, like other Leptus larvae. Southcott (1992) described Leptusmillipedius from julid millipedes, but this is the first record of a parasitic prostigmatan mite from a paradoxosomatid millipede. The only record of a mite from Paradoxosomatidae concerns the widespread Oxidusgracilis (C. L. Koch, 1847) which was reported as associated with Cosmolaelapshortensis Ishikawa, 1986 (Mesostigmata, family Laelapidae) (Ishikawa 1986).

Golovatch and Enghoff (1994) reported one broken male of “Desmoxytes sp.” from Phuket Province, Thailand. According to the remarks of Golovatch and Enghoff (1994), the gonopod characters of this specimen were similar to D.delfae, but the paraterga showed a higher degree of elevation. We examined this specimen again and found it to share gonopod and other characters with D.cervina. We therefore treat “Desmoxytes sp.” as D.cervina.

The name is a Latin noun in apposition, referring to the similarity of the lamina lateralis (ll) to the crest-liked structure on the head of the dinosaur genus Corythosaurus.

Diagnosis.

Body dark brown to black; paraterga with brown or black patches contrasting against whitish at base and along the edges; metaterga 2–18 with rows of 2+2 anterior and 2+2 posterior tubercles. Similar in these respects to D.terae, but differing by having paraterga much longer and higher; sternal lobe between male coxae 4 subtrapeziform; male femora 5 and 6 modified; lamina lateralis (ll) apically crest-like; distal lobe with one very long lamella; indentation between distal lobe (dlm) and broad lobe (blm) inconspicuous.

This species is known only from a narrow distribution range in Phanom district. We consider D.corythosaurus sp. n. to be endemic for Surat Thani Province, Thailand.

Remarks.

The shape of the sternal lobe between male coxae 4 is variable: the tip is emarginate in the populations from Wat Tham Wararam and Tham Nam Lod, whereas specimens from the type locality have a truncate tip. The new species shares a similar shape of gonopodal solenophore with D.terae.

This species is almost impossible to find at first glance. We collected all specimens that were found on the humid rock walls by using flashlight. It blended in perfectly with the brown or black rock, this way probably avoiding being detected by predators.

Coexisting species.

Desmoxytescervina (brown morph) at Ban Song Phi Nong, was collected from rock walls, same habitat as the new species.

The redescription hereunder is modified from Jeekel (1964), and Golovatch and Enghoff (1994). We ‘harmonised’ descriptions of all morphological characters and added some morphological characteristics from additional collected specimens.

Desmoxytesdelfae is known from several provinces in southern Thailand. All new specimens were collected by us from limestone habitats (the recorded locations in previous papers are also limestone); most specimens were seen crawling on leaf litter and climbing on branches of trees (Fig. 30D).

The type locality, Bukit Besar, may be part of what is now Thale Ban National Park in Khuan Don District, Satun Province, and refers to the big mountain which is probably Khao Chin (ca. 2500 ft. or 756 m). Specimens collected by us from Thale Ban National Park may thus be topotypes. The other paratype locality (Bukit Besar, Nawnchila) has not been exactly located, but it is probably near Thale Ban National Park (Thailand–Malaysia border), possibly close to the type locality.

We assume that D.delfae is distributed mainly in Thailand and possibly south to Malaysia near the Thailand–Malaysia border.

This species was reported as endemic for Thailand (Decker 2010), and we would agree that it should be regarded as endemic for the southern part of Thailand due to its narrow distribution. However, two males of D.delfae were reported from Khaosok National Park in west of Surat Thani Province by Decker (2010); it is probable that the specimens from this location belong to another species because all the specimens of D.delfae which we have seen are from an area in south Thailand (Krabi, east of Surat Thaini, Nakhon Si Thammarat, Phatthalung, Satun, Songkhla, and Yala Provinces). Furthermore, Decker (2010) also identified one male, which was collected from Nakhon Si Thammarat Province (Lan Saka District, Khao Luang National Park, near Karom Waterfall) as D.rubra. Re-examination of those specimens in MHNG is necessary to evaluate the distribution of this species.

Remarks.

The remarkable and vivid bright orange colouration is clearly aposematic.

Golovatch and Enghoff (1994) distinguished D.rubra from D.delfae based on D.rubra having 1+1 anterior and 2+2 posterior metatergal tubercles, the mid-dorsal (axial) line traceable, the sternal lobe between male coxae 4 roundly subtriangular and lamina medialis (lm) more strongly produced mesally than dorsally. After examination of all type material and new specimens of both D.delfae and “D.rubra” collected by us, we found that:

– There is a variation in the size of tubercles on metaterga (metaterga with two rows of 2+2 anterior and 2+2 posterior tubercles, lateral tubercles of anterior row in some specimens (tiny and very inconspicuous).

– All specimens are without mid-dorsal line.

– The sternal lobe between male coxae 4 is highly variable in shape, even within populations, as round/ subtrapeziform/ subrectangular; we found this variation in both D.delfae and “D.rubra” specimens. Its tip also varies as subtruncate/ round/ emarginate.

– SEM images clearly show that specimens of these two nominal species have identical gonopods, especially in details of lamina lateralis and lamina medialis.

Due to this variation, we have synonymised D.rubra under D.delfae.

Jeekel (1964) described this species as lacking a tiny denticle near the tip of paraterga on the lateral margin of rings 9, 10, 12, 13, 15–18, and collum as having 2 rows of 3+3 conspicuous setae (anterior row) and 1?+1? inconspicuous tubercles (posterior row). All specimens studied by us have a tiny denticle near the tip (conspicuous in some specimens, inconspicuous in others), and we regard this character as variable within populations.

For D.rubra, Golovatch and Enghoff (1994) described the colour of alcohol-preserved specimens as bright pinkish, that of living specimens as bright red, collum with 3 rows of setae (anterior conspicuous, intermediate and posterior inconspicuous), mid-dorsal line traceable. Based on the re-examination of type material of D.rubra and examination of newly collected specimens we have found that D.rubra (= D.delfae) exhibits:

– Specimens in life with bright orange colouration, newly moulted adult stage pinkish or pinkish orange, late adult stage reddish orange or dark orange. As Golovatch and Enghoff (1994) reported that living specimens have a bright red colour, it is possible that the type specimens of D.rubra were collected at late adult stage (red = reddish orange?).

– Collum with one row of setae (3+3 anterior setae), intermediate and posterior rows absent. Therefore, we here report collum with only one row of setae (3+3 anterior setae).

As we mentioned above, this species shows high variability in morphology, e.g., colour, rows of setae on collum, size of metatergal tubercles, occurrence of a tiny denticle near tip of paraterga, shape of sternal lobe between male coxae 4. All variations are typically present within a population. Although there are deviations in several morphological characters, interestingly, gonopod characters of all specimens are quite stable, looking exactly the same in details.

Differs from all other Desmoxytes species by the combination of the following characters: paraterga knife-like; lateral sulcus (ls) of gonopod shallow; lamina lateralis (ll) separated into two ridges by a deep and wide furrow; process (plm) of lamina medialis long and thin, lamellar, tip dentate or crenate; distal lobe (dlm) of lamina medialis quite long, tip directed ventroanteriad; caudal margin of hypoproct concave or truncate.

Known only from the type locality and nearby areas. This species seems to be rare because we made intensive surveys again in 2015 and 2016, no further specimens were found. As mentioned by Srisonchai et al. (2016), D.des is known only from two localities (Doi Angkhang and Wat Tham Krab), and we consider it to be endemic to Thailand.

Remarks.

This species exhibits some variation in the gonopods: the tip of process (plm) of lamina lateralis is dentate in some specimens, crenate in others. Desmoxytesdes is easy to discriminate from other dragon millipedes by the distinct shape of paraterga and unique gonopod characters.

Coexisting species.

None known.

Corrections to Srisonchai et al. (2016).Srisonchai et al. (2016, pp. 99–103) wrote in the description of this species that paraterga (including paraterga of collum) are directed dorsolaterad at ca. 30°. They are in fact directed caudolaterad and are elevated at ca. 45° as stated in the updated redescription above. Moreover, Srisonchai et al. also described the surface of metaterga as finely shagreened, but we now regard it as being coarsely microgranulate.

Known only from east Thailand (Chantaburi, Chonburi, Sa Kaeo and Rayong Provinces). Interestingly, this species exists in both limestone areas and granitic mountains. It was seen crawling on rocks during the rainy season and occurs only in natural habitat inside primary forest. On the basis of current data, the distribution area is quite narrow, and the species seems to be restricted to the eastern part of Thailand. We thus regard D.euros sp. n. to be an endemic for the Thai fauna.

Remarks.

The observation of all living specimens reveals variation on colour of paraterga within a population; yellow in some specimens, yellowish orange to orange in others.

Desmoxyteseuros sp. n. strongly resembles D.planata in several morphological characters (except for the characters mentioned in the diagnosis); notably the gonopod characters are identical. However, our initial study on DNA barcoding gene (COI) revealed that D.planata and the new species are separated enough to support the suggestion that D.planata and the new species are indeed different species (paper in preparation).

Because of the similarity in gonopod morphology, it is difficult to discriminate old material of D.planata and D.euros sp. n. However, they can be distinguished by colour of paraterga (yellow or yellow orange in D.euros sp. n., pink in D.planata), and by characters of hypoproct (subtriangular in D.euros sp. n., subtrapeziform in D.planata).

We kept several adults in an acrylic box with litter at room temperature. Two weeks later, we found a nest with eggs and a cluster of stadium 1 juveniles at ca. 2 cm depth in the soil and leaf litter (Fig. 37E, F).

Known only from the type locality and a few nearby localities. The new species is restricted to limestone habitats (Fig. 43D), and it is sympatric with D.delfae at Tham Khao Ting and Tham Khan Ti Phol. Unlike the bright orange D.delfae, which was easily spotted crawling on branches of shrubs and on rocks, the new species, blackish brown, was found on rocks where it was quite hard to see. This suggests that these two species, although sharing the same habitat, may show microhabitat differences, but this has not yet been studied in detail. We assume that the new species is distributed along limestone mountain ranges in a narrow area at the border between Trang and Satun Provinces. This species should be regarded as endemic to the Thai fauna.

Metaterga 2–8 with 2+2 tubercles/cones/spines in anterior row and 2+2 tubercles/cones/spines in posterior row; metaterga 9–19 with 3+3 tubercles/cones/spines in posterior row. Similar in these respects to D.breviverpa, D.purpurosea, D.takensis, and D.taurina. Differs from those by having: metaterga 9–19 with two rows of 3(2)+3(2) tubercles/cones/spines in anterior row; lamina lateralis (ll) round and compact; tip of process (plm) of lamina medialis terminating in a sharp spine; distal lobe (dlm) of lamina medialis long; broad lobe (blm) dorsally expanded.

Etymology.

The name honours Sergei I. Golovatch, a myriapodologist at the Institute for Problems of Ecology and Evolution, Russian Academy of Sciences, who has enthusiastically encouraged millipede research in Thailand, in recognition of his extensive work on the taxonomy of millipedes – especially in family Paradoxosomatidae.

Known from the type locality and nearby areas in Kanchanaburi Province only. The type locality is situated on a small, isolated limestone mountain near Khwae Noi River. All specimens were found in limestone habitats (Fig. 49D).

This species is distributed along the limestone mountain ranges in Sai Yok and Thong Pha Phum districts. Based on many intensive surveys, the current distribution of the new species is evidently quite narrow, ca. 100 km2. Thus, D.golovatchi sp. n. should be regarded as a Thai endemic.

Remarks.

Desmoxytesgolovatchi sp. n. is aposematic in its vivid pink body. During the field trips, this animal was noticeable by the contrast of its bright colour to green leaves or brown rocks, it thus was easy to see and collect after rain.

This species is morphologically similar to D.breviverpa, D.purpurosea, D.takensis, and D.waepyanensis sp. n. with which it shares colourful pink or red body colour, as well as further characters, viz., the same patterns of row of cones on metaterga (metaterga 2–8 with 2+2 cones in anterior row).

Coexisting species.

The new species was found in one place together with D.octoconigera sp. n. (see detail in D.octoconigera sp. n.), with D.planata at Wat Huay Charoen Srattha Tham and Tham Khao Noi Bureau of Monks, and with D.purpurosea at Daowadueng Cave. This species and D.purpurosea were hand-collected after rain when lots of them were climbing on vegetation and limestone rocks. Microhabitat differences have not yet been observed. Moreover, D.planata also occurs near the new species, but the habitats of these two species are clearly different: D.planata was found on humid cement and on construction materials whereas D.golovatchi sp. n. was seen crawling on limestone rock.

Differs from all other Desmoxytes species by the combination of the following characters; collum with three rows of 5+5 anterior, 1(2)+1(2) intermediate, and 3+3 posterior setiferous tubercles; metaterga 2–8 with two rows of 3+3 (anterior row) and 3+3 (posterior row) setiferous cones; metaterga 9–17 with two rows of 4(3)+4(3) (anterior row) and 4(5)+4(5) (posterior row) setiferous cones; sternal cone between male coxae 4 incompletely bilobed, cordiform; lateral lamella of distal lobe (dlm) on lamina medialis broad and thin, demarcated from broad lobe (blm) by a deep indentation.

Etymology.

The name is a Latin adjective, referring to the two rows each with eight setiferous cones on metaterga 9–17.

D.octoconigera sp. n. is known only from Kanchanaburi Province. At the type locality where the holotype and the majority of the paratypes were collected, the animals were crawling on litter inside rock holes; some specimens were seen crawling on rock walls near the cave.

Interestingly, some specimens of D.planata were also found near the cave, however, according to our surveys this species is usually found in places with human activity. We assume that it was probably accidentally introduced to the cave by human actions. Therefore, D.planata and the new species might not share microhabitat, although they live syntopically.

The new species and D.golovatchi sp. n. are sympatric in one location at Tham Khao Noi Bureau of Monks (Wat Tham Khao Noi), and they both have narrow distribution ranges (<100 km2). Currently, the type locality of D.octoconigera sp. n. is situated in an area with considerable human activity (Bureau of Monks and tourist cave), where the forest habitat is cut every year.

We have tried in vain to find this species in another area nearby. Given the narrow distribution range, the new species is probably endemic to Thailand.

Remarks.

There is considerable variation in tip of process (plm) of lamina medialis within populations. The process tip in some specimens is bifurcate as two small spines whereas in other specimens it may be relatively blunt.

Differing from all other species, except D.delfae and D.aurata sp. n., by having a low degree of elevation of paraterga, femora 5 and 6 strongly humped ventrally in middle part, collum with a row of 3+3 anterior setae and metaterga 2–18 with rows of 2+2 anterior and 2+2 posterior small tubercles. Differs from D.delfae and D.aurata sp. n. by having paraterga wider than those species; lamina lateralis (ll) with two distinct furrows ventrolaterally; process (plm) of lamina medialis lamellar, tip blunt.

Known only from the type locality. Currently, the habitats at this site are being destroyed and disturbed by human activities, e.g. deforestation for tourist attractions. Our extensive surveys in 2007 allow us to consider this species to be endemic to Malaysia.

Remarks.

D.perakensis sp. n. is morphologically similar to D.delfae and D.aurata sp. n.

Unfortunately, we did not photograph a living specimen during the field trip; however, one collector noticed orange colouration similar to D.aurata sp. n. and D.delfae.

Differs from all other Desmoxytes species by the combination of the following characters; sternal lobe between male coxae 4 subrectangular or subtrapeziform, flattened when seen in lateral view; apical tubercles of epiproct conspicuous, long, digitiform; process (plm) of lamina medialis sharkfin-like, long.

COLOUR: In life with body vivid pink or brownish pink; paraterga vivid pink; metaterga and surface below paraterga brownish pink; head and antenna blackish brown (except distal part of antennomere 7 and antennomere 8 whitish); legs pink or brownish pink; a few basal podomeres whitish pink; sterna brown or pinkish brown; epiproct pink. Colour in alcohol: after two years changed to pale brown.

ANTENNAE: Long and slender, reaching to body ring 5 or end of 5 (male), and 4 (female) when stretched dorsally.

COLLUM: With 3 transverse rows of setiferous tubercles, 3(4)+3(4) anterior, 1+1 intermediate and 2+2 posterior tubercles (excluding small setiferous notches at base of collum paraterga); paraterga of collum low, elevated at ca. 10°–15°, directed almost laterad, with two setiferous notches on lateral margin (first notch located at the base of paratergum, second one conspicuous).

Known only from the type locality and nearby area. It was found in limestone habitats. Given the narrow distribution in the small limestone area in the west of Thung Salaeng Luang National Park (Srisonchai et al. 2016), we regard this species as endemic for Thailand.

Remarks.

We collected additional topotypes during the rainy season. Some morphological variation was found. Thus, in some individuals, the sternal lobe between male coxae 4 is subrectangular, in others subtrapeziform. Gonopod variation is also found in this species; the tip of process (plm) of lamina medialis seems to be slightly blunt in some specimens, slightly sharp in others.

Coexisting species.

None known.

Corrections to Srisonchai et al. (2016)

Srisonchai et al. (2016, pp. 99–103) wrote in the description of this species that the paraterga (including paraterga of collum) are directed dorsolaterad at ca. 30°. They are in fact directed caudolaterad and elevated at ca. as 45°. Moreover, Srisonchai et al. also described the type of tubercles on metaterga as spines in body rings 2–19. We prefer to change terms, from spine to tubercle and cone – thus, metaterga 2–17 with rows of 2+2 anterior cones and 2+2 posterior spines, metaterga 18–19 with rows of 2+2 anterior tubercles and 2+2 posterior tubercles.

This species was collected at several places together with D.octoconigera sp. n., D.golovatchi sp. n. and D.purpurosea, but these species apparently occupy different microhabitats. D.planata can be found all year round in humid places in environments strongly influenced by humans. It was very easy to find, mostly in plant farms or shaded gardens. Although D.planata was sometimes seen in areas close to another Desmoxytes species, the habitats where it was collected are clearly different: D.planata is often found in human-influenced habitats while the other ones live in natural habitats.

However, some specimens from Tham Khoa Ma Rong, Khoa Ta Mong Lai, Ban Yang Chum (all in Prachuap Khiri Khan Province) seem to be indigenous as they were found in limestone habitats, although not too far from human-influenced habitats. Certain introduced paradoxosomatid species seem to have penetrated natural habitats and have become more dominant and abundant than the native ones (Jeekel 1980b), and D.planata at the above-mentioned locations may similarly have dispersed into the forest.

This species has been reported from Hawaii (Chamberlin 1923, 1941). Because the only reliable records concern specimens taken from quarantine in Honolulu, it seems reasonable to delete D.planata from the Hawaii fauna. We believe that this species is transported easily by global commerce, most probably in soil-containing or plant-associated materials.

The origin of D.planata was assumed to be Burma or Malaya by Jeekel (1980a). Later, Shelley and Lehtinen (1998) regarded it more probable that this species occurs naturally in Thailand and China. Based on all recent data analysed by us, D.planata may originally be native to Thailand or Myanmar. Surprisingly, however, no specimen of D.planata has yet been found in Cambodia, Laos, or Malaysia, possibly owing to insufficient surveys in these areas.

Decker (2010) reported D.planata from eastern Thailand, viz., Namtok Phliu (Chantaburi Province), Khao Chamoa National Park (Rayong Province) and Ko Chang National Park (Trat Province). However, these localities all lie in the distribution range of the very similar D.euros sp. n., and Decker’s specimens may well belong to the latter species.

Note on type material.

The lectotype was designated by Mauriès (1980). In the jar which contains lectotype and paralectotypes in NHMUK, there are three small vials:

– a second vial with one male and two female paralectotypes (one female with only rings 10–20), all specimens pinned through the body.

– a third vial with broken specimens (>5 specimens).

There is also one more vial containing many broken and mixed specimens (>15 specimens).

Remarks.

The vivid pink paraterga are obviously aposematic.

According to many previous works, as well as our own results, this species seems to be almost pantropical. In order to assess morphological variability, we compared the gonopods of several specimens (including illustrations) reported from different localities: D.planata from Myanmar (lectotype and paralectotypes); D.coniger – (Jeekel 1980b) from Hawaii taken from Java (Bogor); D.planata – (Mauries 1980) from Seychelles; D.planata – (Shelley and Lehtinen 1998) and (Golovatch and Enghoff 1994) from Fiji; Pratinusrastrituberus – (Zhang, 1986) from China. Combining the examination of previous works and the newly collected specimens from China, Myanmar, and Thailand, variation in morphological characters was as follows.

I. Variation within populations (Fig. 71)

– anterior row of tubercles on collum (usually with 4+4 anterior setae): in some specimens lateral setae located in anterior margin (conspicuous tubercles), in others lateral setae located almost at base of paraterga (inconspicuous tubercles).

On this basis, we strongly agree with Jeekel (1980a) and Golovatch and Enghoff (1994) with the synonymy of D.coniger, E.greeni, E.vector and P.rastrituberus under Desmoxytesplanata. Although the type material of D.coniger in MCZ has not been examined by us, its identity with D.planata is clear from the photo and remarks given by Jeekel (1980a). The morphological characters of this specimen match perfectly with the others.

Desmoxytesplanata is morphologically similar to D.euros sp. n. with which it shares the metaterga with 2+2 anterior tubercles/cones and 2+2 posterior cones/spines. Moreover, gonopod characters of these species are very similar in shape and processes. Based on morphological characters only, they could be supposed to be the same species. However, the colour of living specimens (paraterga) and shape of hypoproct are totally different, as well as ongoing COI analysis supports to separate them as different species.

The updated redescription hereunder is modified from Enghoff et al. 2007; some morphological characteristics have been added which were extracted from the type material and all recently collected specimens.

Known from several places in many provinces (Kampaeng Phet, Kanchanaburi, Lamphun, Suphan Buri, and Uthai Thani). All specimens were collected from limestone habitats (Fig. 75E); they were very easy to collect because of their aposematic colouration. We noticed that August–September is an annual peak period for adult swarming.

Although this species has been found in several places, it is distributed only in central, west, and north Thailand. Hence, D.purpurosea is regarded as endemic for the Thai fauna.

A specimen from Nakhon Sawan Province (Mae Wong National Park, near the type locality of D.purpurosea) which really looks very much like D.purpurosea is shown on YouTube (“shocking pink dragon millipede - living treasure of the forest at Mae Wong National Park” (https://youtu.be/jQsn6rOrlA8 - in Thai)). Although we cannot confirm this record because we did not examine specimens from this location, according to the known distribution of D.purpurosea, the specimen from Nakhon Sawan Province may possibly be this species.

Remarks.

Interestingly, all adult specimens in all populations show exactly the same colour as reported in the original description: vivid pink to purple. However, we found morphological variation between four main populations delimited as follows:

– Size: Specimens from the Lamphun and Uthai Thani populations are larger than others (length 28–34 mm in male, 32–38 mm in female), whereas specimens from the Kanchanaburi B population seems to be smaller than others (length 22–26 mm in male, 26–28 mm).

– Sternal lobe between male coxae 4: The only studied specimen from the Lamphun population has a subsemicircular and quite short lobe, while in others the lobe is trapeziform.

– Apical tubercles of epiproct: Distinctly longer in the Kanchanaburi B population than in others.

– Process (plm) of lamina lateralis: A bifurcate tip, as two conspicuous spines, in the Lamphun and Uthai Thani populations, but terminating in several spines in the Kanchanaburi A and B populations.

The shape of the hypoproct varies within populations: in some specimens it is trapeziform, in others it is subsemicircular.

D.purpurosea shares some morphological characters with D.breviverpa and D.takensis, viz., metaterga 9–19 with rows of 2+2 (anterior) and 3+3 (posterior) setiferous tubercles/cones/spines. However, the differences in gonopod characters are sufficient for separating these as different species.

Differs from all other Desmoxytes species by the combination of the following characters; lamina lateralis (ll) subtriangular; ventral lobe (vll) of lamina lateralis thumb-like, large and long; broad lobe (blm) of lamina medialis indistinctly demarcated from distal lobe (dlm) of lamina medialis by very shallow or slightly deep indentation.

COLOUR (Fig. 82A–D): Population A (see below): In life with body bright red; paraterga, metaterga and surface below paraterga red; head, antennae (distal part of antennomere 7 and antennomere 8 whitish), a few basal podomeres, sterna and epiproct brownish red. Population B (see below): In life with body bright pink; paraterga, metaterga and surface below paraterga bright pink; head brown; antenna blackish brown (except distal part of antennomere 7 and antennomere 8 whitish); legs brownish pink to brown; a few basal podomeres pale brown to whitish; sterna and epiproct brownish pink. Colour in alcohol: after one year changed to pale brown or almost whitish in some specimens.

Known only from Tak and Kamphaeng Phet Provinces. This species is restricted to limestone habitats and was seen crawling on litter and decaying bark (Fig. 82F). Srisonchai et al. (2016) reported that D.takensis was found on humid plastic garbage, a sign that the type locality is clearly under human influence. There is a long, broad concrete natural trail into the waterfall, and lots of garbage littered the type locality. However, the species has also been found in other natural habitats.

During our intensive surveys in western Thailand, we found this species in many places. However, it has a narrow range and occurs in only two provinces. Thus, D.takensis should be regarded to be endemic to the Thai fauna.

– Colour: The remarkable body colour of the two populations apparently differs: bright red in population A, vivid pink in population B (some old females strongly pinkish to reddish).

– Size: Population B individuals seem to be bigger than population A ones in both width and length (see size description).

– Hypoproct: The shape of the hypoproct in population A is subsemicircular whereas it is subtrapeziform in population B.

– Gonopods: The ventral lobe (vll) of lamina lateralis of population B specimens is large, thumb-like, longer, and more slender than that of population A ones. The distal lobe (dlm) of lamina medialis in population A specimens consists of one lamella while population B specimens have two lamellae distally.

Although the two populations vary in some morphological characters, they show an overall gonopodal resemblance. According to the differences in morphology of the two populations, this might an example of ongoing speciation in allopatry, supported by the confinement of the two populations to two large isolated limestone regions located in the northern (Population B) and southern (Population A) parts of the distribution area.

We collected some juveniles during the field trip and kept them with litter until they moulted. Interestingly, the juveniles made a moulting chamber which was apparently produced by fecal material and silk; it is probable that the building process is the same as in the families Polydesmidae, Pyrgodesmidae and in order Callipodida (Adis et al. 2000, Youngsteadt 2009, Reboleira and Enghoff 2016). This is the first observation of moulting in dragon millipedes; however, we did not keep an eye on them in detail. After moulting and emerging from the chamber, the specimens were in an early adult stage showing a pale whitish colouration. Nearly 2 weeks later, they became vivid pink (Fig. 82D, E).

Coexisting species.

None known.

Corrections to Srisonchai et al. (2016)

Srisonchai et al. (2016: 99–103) wrote in the description of this species that the paraterga (including paraterga of collum) are directed dorsolaterad at ca. 30°. They are in fact directed caudolaterad and are elevated at ca. as 45°.

Metaterga 9–19 usually with 2+2 cones/spines (anterior row) and 3+3 cones/spines (posterior row). Similar in this respect to D.breviverpa, D.purpurosea and D.takensis. Differs from these species by the following combination of characters; process (plm) of lamina medialis short, thick and broad, directed mesad, tip blunt; distal lobe (dlm) apically with two distinct lamellae, mesal and lateral lamellae equal in size, very broad and thick; epiproct short; male femora 5 and 6 slightly humped ventrally.

This species is known from Myanmar – Rangoon and Pegu (Taikkyii and Palon). [Rangoon is currently Yangon. Pegu is presently Bago township (Hanthawaddy), Bago region. Taikkyii is Taikkyi township, Yangon region. Palon is probably a small village located in the area north to Taikkyii in the west of Pegu, Yangon region]. Taikkyii and Palon were formerly parts of Pegu region, now they belong to Yangon region. Therefore, the label of specimens collected by Fea gives the locality as Pegu (Taikkyii and Palon).

Habitat details for this species have never been reported; however, all locations are supposed to be granitic and limestone mountain ranges based on geological data, and the two locations were approximately 20 km apart.

We assume that D.taurina is distributed in a narrow range. A field survey near Yangon in 2015 revealed no further specimens of D.taurina. Therefore, we regard this species as endemic to Myanmar.

Note on material.

In the original description Pocock (1895), wrote that all specimens were collected from Rangoon by Oates and from Pegu (Taikkyii and Palon) by Fea. Two females collected by Oates are now in NHMUK, one specimen collected by Fea in ZMH and two males collected by Fea in ZMUC.

The two males in ZMUC collected by Fea are labelled “cotypes”, and only “Palon” is given as locality whereas in the original description Pocock gave “Pegu (Taikkyii and Palon)”. We assume that these two males were probably collected from different locations, one from Taikkyii and one from Palon.

Weidner (1960) classified a specimen (unknown sex, not studied by us) of Prionopeltistaurinus (= Desmoxytestaurina) in ZMH as a “paratypoid”. However, Pocock (1895) and the following authors did not designate a holotype or lectotype for this species, thus, all specimens are syntypes.

The lectotype chosen is the ZMUC male with one remaining gonopod. The other ZMUC, ZMH and NHMUK specimens are designated here as paralectotypes.

Colour of type specimens: the lectotype is brown without metallic oxidation of the pin while the paralectotypes in NHMUK have become greenish black with metallic oxidation of the pin.

Remarks.

This species has not been revised since Golovatch and Enghoff gave a good description in 1994. Golovatch and Enghoff (1994) described the collum with rows of 3(4?)+3(4?) anterior tubercles, suture between prozona and metazona distinctly beaded, pleurosternal carinae absent. After examining all known specimens except the one in ZMH, we found:

We noticed that the number of cones (posterior row) on metaterga varies between individuals. Most specimens have metaterga 8 with 2+2 tubercles in the posterior row, but some have 3+2 tubercles. Metaterga 9–19 usually have 3+3 tubercles in the posterior row, whereas some individuals have with 3+4 or 4+3 tubercles.

The length of antenna in male could not be examined (antennae missing in both males), but the antennae are supposed to reach to ring 5 (Pocock 1895).

Differs from all other Desmoxytes species by the combination of the following characters; body black or brownish black contrasting with yellowish white paraterga with a triangular dorsal, dark spot; sternal lobe between male coxae 4 short and stout, broad at base, trapeziform or semicircular; male femora 5 and 6 without modification; lamina lateralis (ll) with big and long lobe-like structure projecting ventroanteriad.

Type locality.

MALAYSIA, Perlis, Kaki Bukit, near Kampong Wang Tangga.

The redescription hereunder is modified from Jeekel (1964); we ‘harmonised’ descriptions of all morphological characters and added some morphological characteristics from additional specimens.

This species is known only from the Malaysia–Thailand borderland (Kaki Bukit and Thale Ban National Park). We noticed that it prefers to live on humid mosses, logs or litter in limestone habitats (Fig. 88C). The localities are all on limestone mountains. The species is probably distributed in a narrow range in limestone areas near the Thai–Malay border. D.terae has so far been recorded from three localities (near Kaki Bukit, Thale Ban National Park, and Tham Tone Din) which are located only 10–15 km apart. Despite several attempts by us, D.terae was not found in other areas. Hence, this species should be regarded as endemic to the Malaysia and Thailand faunas.

Remarks.

In the recent field surveys we noticed that the colour of living specimens is black or brownish black with contrasting white paraterga as reported earlier by Jeekel (1964) and Golovatch and Enghoff (1994). This species blends so perfectly with its environment that it is difficult to collect specimens without a flashlight.

In the original description, Jeekel (1964) stated about the collum: “near the anterior margin a transverse row of six hairs, which may be present partly rubbed off, the lateral pair placed on the low tubercles”. This means collum with one row of 3+3 anterior setae/tubercles. Moreover, Jeekel also described paraterga without a tiny denticle near the tip. After we examined all specimens, it is clear that:

The sternal lobe between male coxae 4 shows some variation within populations; the lobe of some specimens is trapeziform whereas in others it is semicircular. We also found some variability on the telson: tip of epiproct subtruncate in some individuals, in others slightly emarginate; lateral setiferous tubercles conspicuous in some specimens, inconspicuous in others; caudal margin of hypoproct truncate in some individuals, slightly round in others.

Known only from the type locality in a limestone area (Fig. 93E). We assume that it is distributed in Kayin State. We made an intensive search for this species in September 2016 in Mawlamyine State (very close to Kayin State), however, no further specimens were found. Since it is so far known only from the type locality, D.waepyanensis sp. n. should be regarded as endemic to Myanmar.

Remarks.

The tip of process (plm) on lamina medialis is quite variable, having one, two, or three small spine(s), or being almost blunt in some specimens.

This species seems to be aposematic, to judge by the remarkable pink paraterga and pinkish brown body.

Coexisting species.

None known.

Discussion

Our analyses of morphology, as well as our preliminary molecular phylogeny, supports the subdivision of Desmoxytess.l. into five groups (Desmoxytes s.s., the ‘acantherpestes’group, the ‘gigas’group, the ‘spiny’group and Hylomus). All groups are clearly defined on morphological characters, especially of the gonopods and paraterga (Figs 2, 3). The distribution areas of the groups seem to be clear in their boundaries. The Hylomus group is more diverse in shape of paraterga, however, its members show a notable similarity in gonopod shape (Fig. 2E, F).

Desmoxytes s.s., the focus of the present paper, is well-defined based on gonopod characters especially the solenophore (lamina lateralis (ll) and lamina medialis (lm)). Species of Desmoxytes s.s. share several morphological similarities including wing-like paraterga; lamina lateralis (ll) swollen; lamina medialis (lm) comprised of process (plm), distal lobe (dlm) and broad lobe (blm); and the modification of male femora 5 and 6 only (exception: D.terae). Certain morphological characters show intra- and inter-population variations within the same species. The most variable characters within populations are:

– tubercles/cones/spines on metaterga 9–19: number of tubercles/cones/spines sometimes decrease or increase in some rings – seen in D.taurina, D.purpurosea, D.breviverpa, D.takensis, D.golovatchi sp. n., D.octoconigera sp. n. and D.waepyanensis sp. n. This variable character is not significant for species identification.

– sternal lobe between male coxae 4: many species seem to be variable in the shape of the tip – seen in D.planata, D.cervina, D.delfae, D.purpurosea, D.aurata sp. n., D.corythosaurus sp. n. and D.golovatchi sp. n.

– process (plm) of lamina medialis: tip terminating in one or more spines – seen in D.cervina, D.purpurosea and D.octoconigera sp. n.: tip sharp or blunt – seen in D.breviverpa, D.pinnasquali and D.takensis.

Inter-population variation was also found in some species as follows:

– size: In D.purpurosea, specimens in the two main northern populations are clearly bigger than those from the two main southern populations. Specimens in a population of D.planata from Great Cocos Island seem to be smaller than others.

– colour: colour variation of living specimens of dragon millipedes is reported here for the first time. D.cervina includes brownish red as well as brown individuals. Specimens from the northern populations of D.takensis are red and those from southern populations are pink; however, the other morphological characters are identical.

Variation of colour and size within and between populations may at least in part be due to quality and quantity of food, differences in the physical environment (temperature, soil, humidity), like in other arthropods. Hagen (1881) and Buckton (1879) found that the colour of some arthropods was affected by nutrients and temperature. Many studies, e.g. Baker (1989) and Juliano (1986), have shown that food is one of the main factors controlling growth rate, body size, etc. in arthropods. For millipedes, there is the study by Berns and Keeton (1968) on Narceusannularis (order Spirobolida) showing that semi-starved individuals attained smaller body sizes than well-fed ones. David and Célérier (1997) showed that individuals of Polydesmusangustus kept on a diet of leaf litter plus yeast attained larger body sizes than individuals fed on leaf litter alone. On this background we assume that food and the physical environment may affect colour and size in Desmoxytes. Another possible factor controlling differences in colour and size might be the genetic variation within and between populations.

There are some species showing great resemblance in gonopod characters. In particular, D.planata and D.euros sp. n. are remarkable in having identical gonopods. Nevertheless, the yellow paraterga, shape of hypoproct and the initial study on mitochondrial COI gene supports to separate them as different species. The D.planata-D.euros sp. n. case reminds of what Pimvichai et al. (2011) found for Thyropygusinduratus Attems, 1936 vs T.quietus Attems, 1938: a pair of species with virtually identical gonopods but significant genetic and non-gonopodal morphological differences.

Desmoxytes (and other dragon millipedes) are particularly attractive animals because of the peculiar paraterga, in combination with the unusual vivid colour in some species. The bright colour probably is a warning signal (Svadova et al. 2009, Shear 2015, Marek and Moore 2015). Many mating couples were found during our field surveys, and we collected some representative couples and reared a few specimens of D.euros sp. n. and D.takensis in acrylic boxes, feeding them with natural litter. We observed that the millipedes made moulting chambers using fecal material and silk as found in other polydesmidan families such as Polydesmidae and Pyrgodesmidae, as well as in the order Callipodida (Adis et al. 2000, Youngsteadt 2009, Reboleira and Enghoff 2016). We also observed a host-parasitic association between millipedes and mites in D.cervina (probably the mites belong in genus Leptus Latreille, 1976). We assume that the mite species is a parasite, like in other Leptus spp. (Southcott 1992) which use the millipede host for nourishment and dispersal purposes.

Figs 99 and 100 clearly show that all Desmoxytes species (except D.planata) are narrowly distributed, and all are restricted to limestone habitats or granitic mountains. The narrow distributional ranges of Desmoxytes species are perhaps the result of their poor dispersal capacities.

Desmoxytesplanata, a pantropical species, has been recorded from widely scattered places. According to our survey we suspect that D.planata is probably originally native to Thailand or Myanmar. Especially in Thailand, we noticed that it ranges from Chiang Rai (northern end) to Chumphon Province (middle) (Fig. 100).

Known distribution of all Desmoxytes species based on all recorded data (D.planata, D.cervina and D.delfae are shown in the representative localities).

https://binary.pensoft.net/fig/206450

The species diversity of dragon millipedes is impressive. At the moment, Thailand, Malaysia, and Myanmar contain 18 species of Desmoxytes. We believe that many more new species remain to be discovered, especially in Thailand, Myanmar, Malaysia, Cambodia, and Laos.

Acknowledgements

This work was mainly funded by research grants from the Thailand Research Fund, the TRF Senior Research Scholar (2015–2018), RTA 5880002 and from Center of Excellence on Biodiversity (BDC-PG2-160012) to SP. RS’s visit for one year to the Natural History Museum of Denmark, University of Copenhagen, was supported by a grant from Human Resource Development in Science Project (Science Achievement Scholarship of Thailand (SAST)) and an internal grant from the Natural History Museum of Denmark. We thank all curators who offered, provided and kindly arranged specimen loans for this study: J. Beccaloni at NHMUK, J. Coddington at USNM, Karen van Dorp at NBC, S. I. Golovatch and A. A. Schileyko at ZMUM, R. Pisoni at Verona museum, and also W. Liu (China) for providing information of Chinese species. Thanks are due to the Plant Genetic Conservation Project under the Initiative of Her Royal Highness Maha Chakri Sirindhorn and Center of Excellence on Biodiversity for permission and support in access, also enable us to pursue fieldwork at several restricted/remote areas. We are most grateful to editor R. Mesibov and the referees, N. Akkari, P. Pimvichai, and S. I. Golovatch, for valuable advice and improvement of the manuscript. We express our sincere gratitude to the member of Animal Systematic Research Unit (ASRU) for their kind assistance in all fieldwork and encouragements, especially to C. Sutcharit who offered some specimens. Special thanks go to B. W. Ng (Malaysia), K. Inkhavilay (Laos) and Flora & Fauna International (Myanmar) for collecting specimens outside Thailand. We also thank Ms T. Krutchen for teaching the drawing skills.